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Can I rely on a wrist-strap heart-rate monitor, or should I stick with a chest strap?
—Maya, Los Angeles, CA
When it comes to monitoring the telltale heart, there are two options: chest-strap or wrist-based monitors. Unfortunately, wrist straps aren’t yet accurate enough to guide training.
In January 2017, a group of researchers from the Cleveland Clinic published a letter in the Journal of the American Medical Association Cardiology on the accuracy of wrist-based heart-rate monitors. The researchers had 50 adults use a chest-strap monitor and four different wrist-strap monitors while exercising on a treadmill set to 2 mph, 3 mph, 4 mph, 5 mph and 6 mph. Researchers compared the heart-rate monitor readings against an electrocardiograph (a medical-grade heart-rate monitor used in hospitals). The chest-strap readings had a 0.99 correlation with the electrocardiograph readings. But the wrist straps told a different tale.
The four wrist straps varied between a dismal 0.83 and 0.91 correlation, with higher variation during activity. Sometimes, heart rate varied by as much as 40 beats per minute.
So the technology is exciting, but if you train with heart rate, it’s not time to jettison your chest strap quite yet. If Edgar Allen Poe had had a wrist-strap heart-rate monitor when he wrote his famous story, it might have ended nine- to 17-percent differently.
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